The present application relates generally to an improved data processing apparatus and method and more specifically to an apparatus and method for achieving zero packet loss with energy efficient Ethernet link transition via driver fast failover.
Ethernet is the standard local area network (LAN) access method. Defined by the Institute of Electrical and Electronics Engineers (IEEE) as the 802.3 standard, Ethernet is used to connect computers in a company or home network, as well as to connect a single computer to a cable modem or digital subscriber line (DSL) modem for Internet access.
A 10/100 Ethernet port supports two speeds: 10 Mbps (10Base-T) and 100 Mbps (100Base-T). A 10/100/1000 port includes Gigabit Ethernet at 1 Gbps (1,000 megabits). In the past, Ethernet devices negotiated with each other and transmit at the highest speed possible. Energy Star compliance calls for Energy Efficient Ethernet by 2009. The current direction Ethernet is going to achieve this goal revolves around Adaptive Link Rate (ALR), which is not yet established as an IEEE standard.
Due to the bursty nature of Ethernet traffic, ALR consists of renegotiating the link to low speed during times of low utilization and renegotiating to high speed during heavy utilization. The problem at hand is that ALR will drive new hardware, switch and standards requirements that are not yet available.
Furthermore, a software based solution does not benefit from the draft proposals for hardware/protocol functionality. The link renegotiation requires a link reset, which takes several hundred milliseconds and results in packet drops. The number of packet drops will be proportionate to the line speed (e.g., 10/100/1000/10000 Mbps). Latency sensitive applications, such as streaming traffic from voice over Internet protocol (VoIP) and streaming video, high performance computing (HPC), and non-TCP/IP protocols, are impacted by high latency resulting from dropped packets. Once ALR is in place, it can provide a very fast transition through hardware and protocol functionality, a transition of approximately 10 ms; however, ALR cannot guarantee zero packet loss.